Device and Method for Enhanced Seamless Mobiility

ABSTRACT

Devices and methods of determining offsets for different eNBs in a dynamic switched CoMP network are generally described. A UE may receive, in an RRCConnectionReconfiguration message, DL parameter sets associated with different eNBs and having reference signal information for a PSS, SSS and DRS. The UE may receive reference signals based on the DL set associated with the eNB and determine a timing/frequency offset based on the reference signals. The offsets may be used to decode a dynamically switched PDSCH indicated by a PDCCH. The DL sets may indicate which PDCCH to detect or the PDCCH from the same cNB may be used and the PDSCH determined from a DCI in the PDCCH. A UL DCI may indicate which of UL parameter sets to use. The UL sets may indicate a reference signal to determine path loss and a timing advance value.

PRIORITY CLAIM

This application claims the benefit of priority to U.S. ProvisionalPatent Application Ser. No. 62/217,623, filed Sep. 11, 2015, andentitled “ENHANCED SEAM-LESS MOBILITY SUPPORT FOR LTE-A,” which isincorporated herein by reference in its entirety.

TECHNICAL FIELD

Embodiments pertain to radio access networks. Some embodiments relate tothe use of Coordinated Multipoint (CoMP) in cellular networks, includingThird Generation Partnership Project Long Term Evolution (3GPP LTE)networks and LTE advanced (LTE-A) networks as well as 4^(th) generation(4G) networks and 5^(th) generation (5G) networks.

BACKGROUND

With the increase in different types of devices communicating overnetworks to servers and other computing devices, usage of 3GPP LTEsystems has increased. In particular, as the number and complexity ofuser equipment (UEs) has grown, users have demanded extendedfunctionality and enhanced and varied applications. While the demand fortelephony and messaging services has remained steady. The demand fordata-intensive applications such as video streaming has continued toincrease, increasing the desire for higher transmission rates andstressing network resources. To aid in serving UEs in 3GPP LTE networksusing 4G and beyond, Coordinated Multipoint (CoMP) is beingstandardized.

However, in certain situations handover in CoMP networks may becomeproblematic due to an extensive amount of offset, causing both downlinkand uplink mobility-related issues.

BRIEF DESCRIPTION OF THE FIGURES

In the figures, which are not necessarily drawn to scale, like numeralsmay describe similar components in different views. Like numerals havingdifferent letter suffixes may represent different instances of similarcomponents. The figures illustrate generally, by way of example, but notby way of limitation, various embodiments discussed in the presentdocument.

FIG. 1 is a functional diagram of a wireless network in accordance withsome embodiments.

FIG. 2 illustrates components of a communication device in accordancewith some embodiments.

FIG. 3 illustrates a block diagram of a communication device inaccordance with some embodiments.

FIG. 4 illustrates another block diagram of a communication device inaccordance with some embodiments.

FIG. 5 is a functional diagram of a wireless network using CoMP inaccordance with some embodiments.

FIG. 6 illustrates CoMP using multiple Fast Fourier Transform (FFT)processes in accordance with some embodiments.

FIG. 7 illustrates a flowchart of a method of physical downlink controlchannel (PDCCH) reception in accordance with some embodiments.

DETAILED DESCRIPTION OF THE INVENTION

The following description and the drawings sufficiently illustratespecific embodiments to enable those skilled in the art to practicethem. Other embodiments may incorporate structural, logical, electrical,process, and other changes. Portions and features of some embodimentsmay be included in, or substituted for, those of other embodiments.Embodiments set forth in the claims encompass all available equivalentsof those claims.

FIG. 1 shows an example of a portion of an end-to-end networkarchitecture of a Long Term Evolution (LTE) network with variouscomponents of the network in accordance with some embodiments. As usedherein, an LTE network refers to both LTE and LTE Advanced (LTE-A)networks as well as other versions of LTE networks to be developed. Thenetwork 100 may comprise a radio access network (RAN) (e.g., asdepicted, the E-UTRAN or evolved universal terrestrial radio accessnetwork) 101 and core network 120 (e.g., shown as an evolved packet core(EPC)) coupled together through an S1 interface 115. For convenience andbrevity, only a portion of the core network 120, as well as the RAN 101,is shown in the example.

The core network 120 may include a mobility management entity (MME) 122,serving gateway (serving GW) 124, and packet data network gateway (PDNGW) 126. The RAN 101 may include evolved nodeBs (eNBs) 104 (which mayoperate as base stations) for communicating with user equipment (UE)102. The eNBs 104 may include macro eNBs 104 a and low power (LP) eNBs104 b. The term eNB and cell is used interchangeably herein. The eNBs104 and UEs 102 may employ CoMP techniques as described herein.

The MME 122 may be similar in function to the control plane of legacyServing GPRS Support Nodes (SGSN). The MME 122 may manage mobilityaspects in access such as gateway selection and tracking area listmanagement. The serving GW 124 may terminate the interface toward theRAN 101, and route data packets between the RAN 101 and the core network120. In addition, the serving GW 124 may be a local mobility anchorpoint for inter-eNB handovers and also may provide an anchor forinter-3GPP mobility. Other responsibilities may include lawfulintercept, charging, and some policy enforcement. The serving GW 124 andthe MME 122 may be implemented in one physical node or separate physicalnodes.

The PDN GW 126 may terminate a SGi interface toward the packet datanetwork (PDN). The PDN GW 126 may route data packets between the EPC 120and the external PDN, and may perform policy enforcement and chargingdata collection. The PDN GW 126 may also provide an anchor point formobility devices with non-LTE access. The external PDN can be any kindof IP network, as well as an IP Multimedia Subsystem (IMS) domain. ThePDN GW 126 and the serving GW 124 may be implemented in a singlephysical node or separate physical nodes.

The eNBs 104 (macro and micro) may terminate the air interface protocoland may be the first point of contact for a UE 102. In some embodiments,an eNB 104 may fulfill various logical functions for the RAN 101including, but not limited to, RNC (radio network controller functions)such as radio bearer management, uplink and downlink dynamic radioresource management and data packet scheduling, and mobility management.In accordance with embodiments. UEs 102 may be configured to communicateorthogonal frequency division multiplexed (OFDM) communication signalswith an eNB 104 over a multicarrier communication channel in accordancewith an OFDMA communication technique. The OFDM signals may comprise aplurality of orthogonal subcarriers.

The S1 interface 115 may be the interface that separates the RAN 101 andthe EPC 120. It may be split into two parts: the S1-U, which may carrytraffic data between the eNBs 104 and the serving GW 124, and theS1-MME, which may be a signaling interface between the cNBs 104 and theMME 122. The X2 interface may be the interface between eNBs 104. The X2interface may comprise two parts, the X2-C and X2-U. The X2-C may be thecontrol plane interface between the eNBs 104, while the X2-U may be theuser plane interface between the eNBs 104.

With cellular networks, LP cells 104 b may be typically used to extendcoverage to indoor areas where outdoor signals do not reach well, or toadd network capacity in areas with dense usage. In particular, it may bedesirable to enhance the coverage of a wireless communication systemusing cells of different sizes, macrocells, microcells, picocells, andfemtocells, to boost system performance. The cells of different sizesmay operate on the same frequency band, or may operate on differentfrequency bands with each cell operating in a different frequency bandor only cells of different sizes operating on different frequency bands.As used herein, the term LP eNB refers to any suitable relatively LP eNBfor implementing a smaller cell (smaller than a macro cell) such as afemtocell, a picocell, or a microcell. Femtocell eNBs may be typicallyprovided by a mobile network operator to its residential or enterprisecustomers. A femtocell may be typically the size of a residentialgateway or smaller and generally connect to a broadband line. Thefemtocell may connect to the mobile operator's mobile network andprovide extra coverage in a range of typically 30 to 50 meters. Thus, aLP eNB 104 b might be a femtocell cNB since it is coupled through thePDN GW 126. Similarly, a picocell may be a wireless communication systemtypically covering a small area, such as in-building (offices, shoppingmalls, train stations, etc.), or more recently in-aircraft. A picocelleNB may generally connect through the X2 link to another eNB such as amacro eNB through its base station controller (BSC) functionality. Thus,LP eNB may be implemented with a picocell eNB since it may be coupled toa macro eNB 104 a via an X2 interface. Picocell eNBs or other LP eNBs LPeNB 104 b may incorporate some or all functionality of a macro eNB LPeNB 104 a. In some cases, this may be referred to as an access pointbase station or enterprise femtocell.

Communication over an LTE network may be split up into 10 ms frames,each of which may contain ten 1 ms subframes. Each subframe of theframe, in turn, may contain two slots of 0.5 ms. Each subframe may beused for uplink (UL) communications from the UE to the eNB or downlink(DL) communications from the eNB to the UE. In one embodiment, the eNBmay allocate a greater number of DL communications than ULcommunications in a particular frame. The eNB may schedule transmissionsover a variety of frequency bands (f₁ and f₂). The allocation ofresources in subframes used in one frequency band and may differ fromthose in another frequency band. Each slot of the subframe may contain6-7 OFDM symbols, depending on the system used. In one embodiment, thesubframe may contain 12 subcarriers. A downlink resource grid may beused for downlink transmissions from an eNB to a UE, while an uplinkresource grid may be used for uplink transmissions from a UE to an eNBor from a UE to another UE. The resource grid may be a time-frequencygrid, which is the physical resource in the downlink in each slot. Thesmallest time-frequency unit in a resource grid may be denoted as aresource element (RE). Each column and each row of the resource grid maycorrespond to one OFDM symbol and one OFDM subcarrier, respectively. Theresource grid may contain resource blocks (RBs) that describe themapping of physical channels to resource elements and physical RBs(PRBs). A PRB may be the smallest unit of resources that can beallocated to a UE. A resource block may be 180 kHz wide in frequency and1 slot long in time. In frequency, resource blocks may be either 12×15kHz subcarriers or 24×7.5 kHz subcarriers wide. For most channels andsignals, 12 subcarriers may be used per resource block, dependent on thesystem bandwidth. In Frequency Division Duplexed (FDD) mode, both theuplink and downlink frames may be 10 ms and frequency (full-duplex) ortime (half-duplex) separated. In Time Division Duplexed (TDD), theuplink and downlink subframes may be transmitted on the same frequencyand are multiplexed in the time domain. The duration of the resourcegrid 400 in the time domain corresponds to one subframe or two resourceblocks. Each resource grid may comprise 12 (subcarriers)*14(symbols)=168 resource elements.

Each OFDM symbol may contain a cyclic prefix (CP) which may be used toeffectively eliminate Inter Symbol Interference, and a Fast FourierTransform (FFT) period. The duration of the CP may be determined by thehighest anticipated degree of delay spread Although distortion from thepreceding OFDM symbol may exist within the CP, with a CP of sufficientduration, preceding OFDM symbols do not enter the FFT period. Once theFFT period signal is received and digitized, the receiver may ignore thesignal in the CP.

There may be several different physical downlink channels that areconveyed using such resource blocks, including the physical downlinkcontrol channel (PDCCH) and the physical downlink shared channel(PDSCH). Each subframe may be partitioned into the PDCCH and the PDSCH.The PDCCH may normally occupy the first two symbols of each subframe andcarries, among other things, information about the transport format andresource allocations related to the PDSCH channel, as well as H-ARQinformation related to the uplink shared channel. The PDSCH may carryuser data and higher layer signaling to a UE and occupy the remainder ofthe subframe. Typically, downlink scheduling (assigning control andshared channel resource blocks to UEs within a cell) may be performed atthe eNB based on channel quality information provided from the UEs tothe eNB, and then the downlink resource assignment information may besent to each UE on the PDCCH used for (assigned to) the UE.

The PDCCH may contain downlink control information (DCI) in one of anumber of formats that tell the UE how to find and decode data,transmitted on PDSCH in the same subframe, from the resource grid. TheDCI format may provide details such as number of resource blocks,resource allocation type, modulation scheme, transport block, redundancyversion, coding rate etc. Each DCI format may have a cyclic redundancycode (CRC) and be scrambled with a Radio Network Temporary Identifier(RNTI) that identifies the target UE for which the PDSCH is intended.Use of the UE-specific RNTI may limit decoding of the DCI format (andhence the corresponding PDSCH) to only the intended UE. In addition toreceiving downlink transmissions, the UE 102 may transmit uplinkinformation to an cNB 104 a, 104 b via a Physical Uplink Shared Channel(PUSCH). The PUSCH may carry RRC messages, Uplink Control Information(UCI) and data.

In addition to the PDCCH, an enhanced PDCCH (cPDCCH) may be used. ThePDSCH may contain data in some of the RBs and the ePDCCH may contain thedownlink control signals in others of the RBs of the bandwidth supportedby the UE 102. Different UEs may have different ePDCCH configurations.The sets of RBs corresponding to ePDCCH may be configured, for example,by higher layer signaling such as Radio Resource Control (RRC) signalingfor ePDCCH monitoring.

Periodic reference signaling messages containing reference signals mayoccur between the eNB and the UEs. The downlink reference signals mayinclude cell-specific reference signal (CRS) and UE-specific referencesignals. The CRS may be used for scheduling transmissions to multipleUEs, channel estimation, coherent demodulation at the UE and handover.CRS may, however, be usable only with 2 or 4 antennas. CRS may betransmitted in each sixth subcarrier during the first and fifth OFDMsymbols of each slot when the short CP is used and during the first andfourth OFDM symbols when the long CP is used. Other reference signalsmay include a channel state information reference signal (CSI-RS) usedfor measurement purposes, and a Discovery Reference Signal (DRS)specific to an individual UE. CSI-RS are relatively sparse, occur in thePDSCH and are antenna dependent. The Primary Synchronization Signal(PSS) and Secondary Synchronization Signal (SSS) may be used by the UEto identify the cell using the physical cell ID (PCID), the currentsubframe number, slot boundary, and duplexing mode. The PSS and SSS maybe sent in the center 1.08 MHz of the system bandwidth used by the eNBin a broadcast to all UEs in symbol periods 6 and 5, respectively, ineach of subframes 0 and 5 of each radio frame with a normal CP, toMultimedia Broadcast Multicast Service Single Frequency Network (MBSFN)reference signals used to provide Evolved Multimedia Broadcast MulticastServices (eMBMS) to the UE.

The above and other periodic messages thus not only provide informationregarding the communication channel, but also enable tracking in timeand/or frequency of communications with the UE. The uplink referencesignals may include Demodulation Reference Signals (DM-RS), which may beused to enable coherent signal demodulation at the eNB. DM-RS may betime multiplexed with uplink data and transmitted on the fourth or thirdsymbol of an uplink slot for normal or extended CP, respectively, usingthe same bandwidth as the data. Sounding Reference Signals (SRS) may beused by UEs with different transmission bandwidth to allow channeldependent uplink scheduling and may typically be transmitted in the lastsymbol of a subframe.

The eNBs 104 and UEs 102 may employ CoMP for transmission and reception.In downlink CoMP, the eNBs 104 may provide overlapping coverage and maycoordinate transmissions to a UE 102. In uplink CoMP, the reception ofUE signals may be coordinated among the eNBs 104 to improve networkperformance at cell edges. In some embodiment, the eNBs 104 providingthe overlapping coverage may be a homogeneous set of macro eNBs 104 awhile in other embodiments the eNBs 104 may be heterogeneous, includinga macro cNB 104 a and a LP eNB 104 b. The eNBs 104 may be geographicallyseparated but dynamically coordinated through a high-speed backhaul toprovide joint scheduling and transmissions as well as proving jointprocessing of the received signals.

CoMP may employed in different techniques, which include JointProcessing, Dynamic Point Selection and Coordinatedscheduling/beamforming. In Joint Processing, the eNBs 104 may transmitdata on the same frequency in the same subframe and/or uplinktransmissions from the UE 102 may be received by the eNBs 104 andcombined to improve the signal quality and strength and perhaps activelycancel interference from transmissions that are intended for other UEs.This may increase the amount of data in the network dependent upon howmany eNBs 104 transmit the data. Uplink transmissions from the UE 102may be detected by antennas at the different eNBs 104, which may form avirtual antenna array. The signals received by the eNBs 104 may becombined and processed to increase the strength of low strength signalsor those masked by interference. In Dynamic Point Selection, data mayavailable for transmission at multiple eNBs 104 but only scheduled fromcNB 104 in each subframe. In Coordinated scheduling/beamforming, eacheNB 104 in the CoMP area may transmit data to the UE 102 in differentsubframes while scheduling decisions as well as beam coordination arecoordinated among the eNBs 104. In some embodiments, blanking or mutingof signals from one eNB 104 may be used when another eNB is transmittingto decrease interference.

Embodiments described herein may be implemented into a system using anysuitably configured hardware and/or software. FIG. 2 illustratescomponents of a UE in accordance with some embodiments. At least some ofthe components shown may be used in an eNB or MME, for example, such asthe UE 102 or eNB 104 shown in FIG. 1. The UE 200 and other componentsmay be configured to use the CoMP framework as described herein. The UE200 may be one of the UEs 102 shown in FIG. 1 and may be a stationary,non-mobile device or may be a mobile device. In some embodiments, the UE200 may include application circuitry 202, baseband circuitry 204, RadioFrequency (RF) circuitry 206, front-end module (FEM) circuitry 208 andone or more antennas 210, coupled together at least as shown. At leastsome of the baseband circuitry 204. RF circuitry 206, and FEM circuitry208 may form a transceiver. In some embodiments, other network elements,such as the eNB may contain some or all of the components shown in FIG.2. Other of the network elements, such as the MME, may contain aninterface, such as the S1 interface, to communicate with the cNB over awired connection regarding the UE.

The application or processing circuitry 202 may include one or moreapplication processors. For example, the application circuitry 202 mayinclude circuitry such as, but not limited to, one or more single-coreor multi-core processors. The processor(s) may include any combinationof general-purpose processors and dedicated processors (e.g., graphicsprocessors, application processors, etc.). The processors may be coupledwith and/or may include memory/storage and may be configured to executeinstructions stored in the memory/storage to enable various applicationsand/or operating systems to run on the system.

The baseband circuitry 204 may include circuitry such as, but notlimited to, one or more single-core or multi-core processors. Thebaseband circuitry 204 may include one or more baseband processorsand/or control logic to process baseband signals received from a receivesignal path of the RF circuitry 206 and to generate baseband signals fora transmit signal path of the RF circuitry 206. Baseband processingcircuitry 204 may interface with the application circuitry 202 forgeneration and processing of the baseband signals and for controllingoperations of the RF circuitry 206. For example, in some embodiments,the baseband circuitry 204 may include a second generation (2G) basebandprocessor 204 a, third generation (3G) baseband processor 204 b, fourthgeneration (4G) baseband processor 204 c, and/or other basebandprocessor(s) 204 d for other existing generations, generations indevelopment or to be developed in the future (e.g., fifth generation(5G), 6G, etc.). The baseband circuitry 204 (e.g., one or more ofbaseband processors 204 a-d) may handle various radio control functionsthat enable communication with one or more radio networks via the RFcircuitry 206. The radio control functions may include, but are notlimited to, signal modulation/demodulation, encoding/decoding, radiofrequency shifting, etc. In some embodiments, modulation/demodulationcircuitry of the baseband circuitry 204 may include FFT, precoding,and/or constellation mapping/demapping functionality. In someembodiments, encoding/decoding circuitry of the baseband circuitry 204may include convolution, tail-biting convolution, turbo, Viterbi, and/orLow Density Parity Check (LDPC) encoder/decoder functionality.Embodiments of modulation/demodulation and encoder/decoder functionalityare not limited to these examples and may include other suitablefunctionality in other embodiments.

In some embodiments, the baseband circuitry 204 may include elements ofa protocol stack such as, for example, elements of an evolved universalterrestrial radio access network (EUTRAN) protocol including, forexample, physical (PHY), media access control (MAC), radio link control(RLC), packet data convergence protocol (PDCP), and/or RRC elements. Acentral processing unit (CPU) 204 e of the baseband circuitry 204 may beconfigured to run elements of the protocol stack for signaling of thePHY, MAC, RLC, PDCP and/or RRC layers. In some embodiments, the basebandcircuitry may include one or more audio digital signal processor(s)(DSP) 204 f. The audio DSP(s) 204 f may be include elements forcompression/decompression and echo cancellation and may include othersuitable processing elements in other embodiments. Components of thebaseband circuitry may be suitably combined in a single chip, a singlechipset, or disposed on a same circuit board in some embodiments. Insome embodiments, some or all of the constituent components of thebaseband circuitry 204 and the application circuitry 202 may beimplemented together such as, for example, on a system on a chip (SOC).

In some embodiments, the baseband circuitry 204 may provide forcommunication compatible with one or more radio technologies. Forexample, in some embodiments, the baseband circuitry 204 may supportcommunication with an evolved universal terrestrial radio access network(EUTRAN) and/or other wireless metropolitan area networks (WMAN), awireless local area network (WLAN), a wireless personal area network(WPAN). Embodiments in which the baseband circuitry 204 is configured tosupport radio communications of more than one wireless protocol may bereferred to as multi-mode baseband circuitry. In some embodiments, thedevice can be configured to operate in accordance with communicationstandards or other protocols or standards, including Institute ofElectrical and Electronic Engineers (IEEE) 802.16 wireless technology(WiMax), IEEE 802.11 wireless technology (WiFi) including IEEE 802 ad,which operates in the 60 GHz millimeter wave spectrum, various otherwireless technologies such as global system for mobile communications(GSM), enhanced data rates for GSM evolution (EDGE), GSM EDGE radioaccess network (GERAN), universal mobile telecommunications system(UNITS), UMTS terrestrial radio access network (UTRAN), or other 2G, 3G,4G, 5G, etc. technologies either already developed or to be developed.

RF circuitry 206 may enable communication with wireless networks usingmodulated electromagnetic radiation through a non-solid medium. Invarious embodiments, the RF circuitry 206 may include switches, filters,amplifiers, etc. to facilitate the communication with the wirelessnetwork. RF circuitry 206 may include a receive signal path which mayinclude circuitry to down-convert RF signals received from the FEMcircuitry 208 and provide baseband signals to the baseband circuitry204. RF circuitry 206 may also include a transmit signal path which mayinclude circuitry to up-convert baseband signals provided by thebaseband circuitry 204 and provide RF output signals to the FEMcircuitry 208 for transmission.

In some embodiments, the RF circuitry 206 may include a receive signalpath and a transmit signal path. The receive signal path of the RFcircuitry 206 may include mixer circuitry 206 a, amplifier circuitry 206b and filter circuitry 206 c. The transmit signal path of the RFcircuitry 206 may include filter circuitry 206 c and mixer circuitry 206a. RF circuitry 206 may also include synthesizer circuitry 206 d forsynthesizing a frequency for use by the mixer circuitry 206 a of thereceive signal path and the transmit signal path. In some embodiments,the mixer circuitry 206 a of the receive signal path may be configuredto down-convert RF signals received from the FEM circuitry 208 based onthe synthesized frequency provided by synthesizer circuitry 206 d. Theamplifier circuitry 206 b may be configured to amplify thedown-converted signals and the filter circuitry 206 c may be a low-passfilter (LPF) or band-pass filter (BPF) configured to remove unwantedsignals from the down-converted signals to generate output basebandsignals. Output baseband signals may be provided to the basebandcircuitry 204 for further processing. In some embodiments, the outputbaseband signals may be zero-frequency baseband signals, although thisis not a requirement. In some embodiments, mixer circuitry 206 a of thereceive signal path may comprise passive mixers, although the scope ofthe embodiments is not limited in this respect.

In some embodiments, the mixer circuitry 206 a of the transmit signalpath may be configured to up-convert input baseband signals based on thesynthesized frequency provided by the synthesizer circuitry 206 d togenerate RF output signals for the FEM circuitry 208. The basebandsignals may be provided by the baseband circuitry 204 and may befiltered by filter circuitry 206 c. The filter circuitry 206 c mayinclude a low-pass filter (LPF), although the scope of the embodimentsis not limited in this respect.

In some embodiments, the mixer circuitry 206 a of the receive signalpath and the mixer circuitry 206 a of the transmit signal path mayinclude two or more mixers and may be arranged for quadraturedownconversion and/or upconversion respectively. In some embodiments,the mixer circuitry 206 a of the receive signal path and the mixercircuitry 206 a of the transmit signal path may include two or moremixers and may be arranged for image rejection (e.g., Hartley imagerejection). In some embodiments, the mixer circuitry 206 a of thereceive signal path and the mixer circuitry 206 a may be arranged fordirect downconversion and/or direct upconversion, respectively. In someembodiments, the mixer circuitry 206 a of the receive signal path andthe mixer circuitry 206 a of the transmit signal path may be configuredfor super-heterodyne operation.

In some embodiments, the output baseband signals and the input basebandsignals may be analog baseband signals, although the scope of theembodiments is not limited in this respect. In some alternateembodiments, the output baseband signals and the input baseband signalsmay be digital baseband signals. In these alternate embodiments, the RFcircuitry 206 may include analog-to-digital converter (ADC) anddigital-to-analog converter (DAC) circuitry and the baseband circuitry204 may include a digital baseband interface to communicate with the RFcircuitry 206.

In some dual-mode embodiments, a separate radio IC circuitry may beprovided for processing signals for each spectrum, although the scope ofthe embodiments is not limited in this respect.

In some embodiments, the synthesizer circuitry 206 d may be afractional-N synthesizer or a fractional N/N+1 synthesizer, although thescope of the embodiments is not limited in this respect as other typesof frequency synthesizers may be suitable. For example, synthesizercircuitry 206 d may be a delta-sigma synthesizer, a frequencymultiplier, or a synthesizer comprising a phase-locked loop with afrequency divider.

The synthesizer circuitry 206 d may be configured to synthesize anoutput frequency for use by the mixer circuitry 206 a of the RFcircuitry 206 based on a frequency input and a divider control input. Insome embodiments, the synthesizer circuitry 206 d may be a fractionalN/N+1 synthesizer.

In some embodiments, frequency input may be provided by a voltagecontrolled oscillator (VCO), although that is not a requirement. Dividercontrol input may be provided by either the baseband circuitry 204 orthe applications processor 202 depending on the desired outputfrequency. In some embodiments, a divider control input (e.g., N) may bedetermined from a look-up table based on a channel indicated by theapplications processor 202.

Synthesizer circuitry 206 d of the RF circuitry 206 may include adivider, a delay-locked loop (DLL), a multiplexer and a phaseaccumulator. In some embodiments, the divider may be a dual modulusdivider (DMD) and the phase accumulator may be a digital phaseaccumulator (DPA). In some embodiments, the DMD may be configured todivide the input signal by either N or N+1 (e.g., based on a carry out)to provide a fractional division ratio. In some example embodiments, theDLL may include a set of cascaded, tunable, delay elements, a phasedetector, a charge pump and a D-type flip-flop. In these embodiments,the delay elements may be configured to break a VCO period up into Ndequal packets of phase, where Nd is the number of delay elements in thedelay line. In this way, the DLL provides negative feedback to helpensure that the total delay through the delay line is one VCO cycle.

In some embodiments, synthesizer circuitry 206 d may be configured togenerate a carrier frequency as the output frequency, while in otherembodiments, the output frequency may be a multiple of the carrierfrequency (e.g., twice the carrier frequency, four times the carrierfrequency) and used in conjunction with quadrature generator and dividercircuitry to generate multiple signals at the carrier frequency withmultiple different phases with respect to each other. In someembodiments, the output frequency may be a LO frequency (f_(LO)). Insome embodiments, the RF circuitry 206 may include an IQ/polarconverter.

FEM circuitry 208 may include a receive signal path which may includecircuitry configured to operate on RF signals received from one or moreantennas 210, amplify the received signals and provide the amplifiedversions of the received signals to the RF circuitry 206 for furtherprocessing. FEM circuitry 208 may also include a transmit signal pathwhich may include circuitry configured to amplify signals fortransmission provided by the RF circuitry 206 for transmission by one ormore of the one or more antennas 210.

In some embodiments, the FEM circuitry 208 may include a TX/RX switch toswitch between transmit mode and receive mode operation. The FEMcircuitry may include a receive signal path and a transmit signal path.The receive signal path of the FEM circuitry may include a low-noiseamplifier (LNA) to amplify received RF signals and provide the amplifiedreceived RF signals as an output (e.g., to the RF circuitry 206). Thetransmit signal path of the FEM circuitry 208 may include a poweramplifier (PA) to amplify input RF signals (e.g., provided by RFcircuitry 206), and one or more filters to generate RF signals forsubsequent transmission (e.g., by one or more of the one or moreantennas 210.

In some embodiments, the UE 200 may include additional elements such as,for example, memory/storage, display, camera, sensor, and/orinput/output (I/O) interface as described in more detail below. In someembodiments, the UE 200 described herein may be part of a portablewireless communication device, such as a personal digital assistant(PDA), a laptop or portable computer with wireless communicationcapability, a web tablet, a wireless telephone, a smartphone, a wirelessheadset, a pager, an instant messaging device, a digital camera, anaccess point, a television, a medical device (e.g., a heart ratemonitor, a blood pressure monitor, etc.), or other device that mayreceive and/or transmit information wirelessly. In some embodiments, theUE 200 may include one or more user interfaces designed to enable userinteraction with the system and/or peripheral component interfacesdesigned to enable peripheral component interaction with the system. Forexample, the UE 200 may include one or more of a keyboard, a keypad, atouchpad, a display, a sensor, a non-volatile memory port, a universalserial bus (USB) port, an audio jack, a power supply interface, one ormore antennas, a graphics processor, an application processor, aspeaker, a microphone, and other I/O components. The display may be anLCD or LED screen including a touch screen. The sensor may include agyro sensor, an accelerometer, a proximity sensor, an ambient lightsensor, and a positioning unit. The positioning unit may communicatewith components of a positioning network, e.g., a global positioningsystem (GPS) satellite.

The antennas 210 may comprise one or more directional or omnidirectionalantennas, including, for example, dipole antennas, monopole antennas,patch antennas, loop antennas, microstrip antennas or other types ofantennas suitable for transmission of RF signals. In some multiple-inputmultiple-output (MIMO) embodiments, the antennas 210 may be effectivelyseparated to take advantage of spatial diversity and the differentchannel characteristics that may result.

Although the UE 200 is illustrated as having several separate functionalelements, one or more of the functional elements may be combined and maybe implemented by combinations of software-configured elements, such asprocessing elements including digital signal processors (DSPs), and/orother hardware elements. For example, some elements may comprise one ormore microprocessors, DSPs, field-programmable gate arrays (FPGAs),application specific integrated circuits (ASICs), radio-frequencyintegrated circuits (RFICs) and combinations of various hardware andlogic circuitry for performing at least the functions described herein.In some embodiments, the functional elements may refer to one or moreprocesses operating on one or more processing elements.

Embodiments may be implemented in one or a combination of hardware,firmware and software. Embodiments may also be implemented asinstructions stored on a computer-readable storage device, which may beread and executed by at least one processor to perform the operationsdescribed herein. A computer-readable storage device may include anynon-transitory mechanism for storing information in a form readable by amachine (e.g., a computer). For example, a computer-readable storagedevice may include read-only memory (ROM), random-access memory (RAM),magnetic disk storage media, optical storage media, flash-memorydevices, and other storage devices and media. Some embodiments mayinclude one or more processors and may be configured with instructionsstored on a computer-readable storage device.

FIG. 3 is a block diagram of a communication device in accordance withsome embodiments. The device may be a UE or eNB, for example, such asthe UE 102 or eNB 104 shown in FIG. 1 that may be configured to usedynamic switching in a CoMP network as described herein. The physicallayer circuitry 302 may perform various encoding and decoding functionsthat may include formation of baseband signals for transmission anddecoding of received signals. The communication device 300 may alsoinclude medium access control layer (MAC) circuitry 304 for controllingaccess to the wireless medium. The communication device 300 may alsoinclude processing circuitry 306, such as one or more single-core ormulti-core processors, and memory 308 arranged to perform the operationsdescribed herein. The physical layer circuitry 302, MAC circuitry 304and processing circuitry 306 may handle various radio control functionsthat enable communication with one or more radio networks compatiblewith one or more radio technologies. The radio control functions mayinclude signal modulation, encoding, decoding, radio frequency shifting,etc. For example, similar to the device shown in FIG. 2, in someembodiments, communication may be enabled with one or more of a WMAN, aWLAN, and a WPAN. In some embodiments, the communication device 300 canbe configured to operate in accordance with 3GPP standards or otherprotocols or standards, including WiMax, WiFi, GSM, EDGE, GERAN, UMTS,UTRAN, or other 3G, 3G, 4G, 5G, etc. technologies either alreadydeveloped or to be developed. The communication device 300 may includetransceiver circuitry 312 to enable communication with other externaldevices wirelessly and interfaces 314 to enable wired communication withother external devices. As another example, the transceiver circuitry312 may perform various transmission and reception functions such asconversion of signals between a baseband range and a Radio Frequency(RF) range.

The antennas 301 may comprise one or more directional or omnidirectionalantennas, including, for example, dipole antennas, monopole antennas,patch antennas, loop antennas, microstrip antennas or other types ofantennas suitable for transmission of RF signals. In some MIMOembodiments, the antennas 301 may be effectively separated to takeadvantage of spatial diversity and the different channel characteristicsthat may result.

Although the communication device 300 is illustrated as having severalseparate functional elements, one or more of the functional elements maybe combined and may be implemented by combinations ofsoftware-configured elements, such as processing elements includingDSPs, and/or other hardware elements. For example, some elements maycomprise one or more microprocessors, DSPs, FPGAs, ASICs. RFICs andcombinations of various hardware and logic circuitry for performing atleast the functions described herein. In some embodiments, thefunctional elements may refer to one or more processes operating on oneor more processing elements. Embodiments may be implemented in one or acombination of hardware, firmware and software. Embodiments may also beimplemented as instructions stored on a computer-readable storagedevice, which may be read and executed by at least one processor toperform the operations described herein.

FIG. 4 illustrates another block diagram of a communication device inaccordance with some embodiments. In alternative embodiments, thecommunication device 400 may operate as a standalone device or may beconnected (e.g., networked) to other communication devices. In anetworked deployment, the communication device 400 may operate in thecapacity of a server communication device, a client communicationdevice, or both in server-client network environments. In an example,the communication device 400 may act as a peer communication device inpeer-to-peer (P2P) (or other distributed) network environment. Thecommunication device 400 may be a UE, eNB, PC, a tablet PC, a STB, aPDA, a mobile telephone, a smart phone, a web appliance, a networkrouter, switch or bridge, or any communication device capable ofexecuting instructions (sequential or otherwise) that specify actions tobe taken by that communication device. Further, while only a singlecommunication device is illustrated, the term “communication device”shall also be taken to include any collection of communication devicesthat individually or jointly execute a set (or multiple sets) ofinstructions to perform any one or more of the methodologies discussedherein, such as cloud computing, software as a service (SaaS), othercomputer cluster configurations.

Examples, as described herein, may include, or may operate on, logic ora number of components, modules, or mechanisms. Modules are tangibleentities (e.g., hardware) capable of performing specified operations andmay be configured or arranged in a certain manner. In an example,circuits may be arranged (e.g., internally or with respect to externalentities such as other circuits) in a specified manner as a module. Inan example, the whole or part of one or more computer systems (e.g., astandalone, client or server computer system) or one or more hardwareprocessors may be configured by firmware or software (e.g.,instructions, an application portion, or an application) as a modulethat operates to perform specified operations. In an example, thesoftware may reside on a communication device readable medium. In anexample, the software, when executed by the underlying hardware of themodule, causes the hardware to perform the specified operations.

Accordingly, the term “module” is understood to encompass a tangibleentity, be that an entity that is physically constructed, specificallyconfigured (e.g., hardwired), or temporarily (e.g., transitorily)configured (e.g., programmed) to operate in a specified manner or toperform part or all of any operation described herein. Consideringexamples in which modules are temporarily configured, each of themodules need not be instantiated at any one moment in time. For example,where the modules comprise a general-purpose hardware processorconfigured using software, the general-purpose hardware processor may beconfigured as respective different modules at different times Softwaremay accordingly configure a hardware processor, for example, toconstitute a particular module at one instance of time and to constitutea different module at a different instance of time.

Communication device (e.g., computer system) 400 may include a hardwareprocessor 402 (e.g., a central processing unit (CPU), a graphicsprocessing unit (GPU), a hardware processor core, or any combinationthereof), a main memory 404 and a static memory 406, some or all ofwhich may communicate with each other via an interlink (e.g., bus) 408.The communication device 400 may further include a display unit 410, analphanumeric input device 412 (e.g., a keyboard), and a user interface(UI) navigation device 414 (e.g., a mouse). In an example, the displayunit 410, input device 412 and UI navigation device 414 may be a touchscreen display. The communication device 400 may additionally include astorage device (e.g., drive unit) 416, a signal generation device 418(e.g., a speaker), a network interface device 420, and one or moresensors 421, such as a global positioning system (GPS) sensor, compass,accelerometer, or other sensor. The communication device 400 may includean output controller 428, such as a serial (e.g., universal serial bus(USB), parallel, or other wired or wireless (e.g., infrared (IR), nearfield communication (NFC), etc.) connection to communicate or controlone or more peripheral devices (e.g., a printer, card reader, etc.).

The storage device 416 may include a communication device readablemedium 422 on which is stored one or more sets of data structures orinstructions 424 (e.g., software) embodying or utilized by any one ormore of the techniques or functions described herein. The instructions424 may also reside, completely or at least partially, within the mainmemory 404, within static memory 406, or within the hardware processor402 during execution thereof by the communication device 40). In anexample, one or any combination of the hardware processor 402, the mainmemory 404, the static memory 406, or the storage device 416 mayconstitute communication device readable media.

While the communication device readable medium 422 is illustrated as asingle medium, the term “communication device readable medium” mayinclude a single medium or multiple media (e.g., a centralized ordistributed database, and/or associated caches and servers) configuredto store the one or more instructions 424.

The term “communication device readable medium” may include any mediumthat is capable of storing, encoding, or carrying instructions forexecution by the communication device 400 and that cause thecommunication device 400 to perform any one or more of the techniques ofthe present disclosure, or that is capable of storing, encoding orcarrying data structures used by or associated with such instructions.Non-limiting communication device readable medium examples may includesolid-state memories, and optical and magnetic media. Specific examplesof communication device readable media may include: non-volatile memory,such as semiconductor memory devices (e.g., Electrically ProgrammableRead-Only Memory (EPROM), Electrically Erasable Programmable Read-OnlyMemory (EEPROM)) and flash memory devices, magnetic disks, such asinternal hard disks and removable disks; magneto-optical disks: RandomAccess Memory (RAM); and CD-ROM and DVD-ROM disks. In some examples,communication device readable media may include non-transitorycommunication device readable media. In some examples, communicationdevice readable media may include communication device readable mediathat is not a transitory propagating signal.

The instructions 424 may further be transmitted or received over acommunications network 426 using a transmission medium via the networkinterface device 420 utilizing any one of a number of transfer protocols(e.g., frame relay, internet protocol (IP), transmission controlprotocol (TCP), user datagram protocol (UDP), hypertext transferprotocol (HTTP), etc.). Example communication networks may include alocal area network (LAN), a wide area network (WAN), a packet datanetwork (e.g., the Internet), mobile telephone networks (e.g., cellularnetworks), Plain Old Telephone (POTS) networks, and wireless datanetworks (e.g., Institute of Electrical and Electronics Engineers (IEEE)802.11 family of standards known as Wi-Fi®, IEEE 802.16 family ofstandards known as WiMax®), IEEE 802.15.4 family of standards, a LongTerm Evolution (LTE) family of standards, a Universal MobileTelecommunications System (UMTS) family of standards, peer-to-peer (P2P)networks, among others. In an example, the network interface device 420may include one or more physical jacks (e.g., Ethernet, coaxial, orphone jacks) or one or more antennas to connect to the communicationsnetwork 426. In an example, the network interface device 420 may includea plurality of antennas to wirelessly communicate using at least one ofsingle-input multiple-output (SIMO), MIMO, or multiple-inputsingle-output (MISO) techniques. In some examples, the network interfacedevice 420 may wirelessly communicate using Multiple User MIMOtechniques. The term “transmission medium” shall be taken to include anyintangible medium that is capable of storing, encoding or carryinginstructions for execution by the communication device 400, and includesdigital or analog communications signals or other intangible medium tofacilitate communication of such software.

FIG. 5 is a functional diagram of a wireless network using CoMP inaccordance with some embodiments. Specifically, FIG. 5 illustrates anexample of CoMP scenario 3, a heterogeneous network in which a macro eNB512 having a macro cell 510 coverage area and a LP eNB 522 having a LPcell 520 coverage area have different cell-IDs. While a UE 502 in theCoMP network may synchronize with one eNB (the synchronization source),in practice communications between the UE and a different eNB (thetransmission point) may encounter a time and/or frequency mismatch evenif the eNBs themselves are synchronized. This mismatch may be extensivein situations in which there is a large difference in propagation delaysbetween the synchronization source and the transmission point.

As above, CoMP with single FFT processing may be used to provideseamless mobility support for UEs in an LTE system. A UE 502 in thedownlink first synchronizes with a single eNB 512 using CRS transmittedby the cNB 512. This eNB may be referred to as the synchronizing sourceor serving cell. The synchronizing eNB is typically a macro eNB 512. TheUE 502 may also receive data when in a LP cell 520 from a LP eNB 522,which, as above may be a micro, pico or nano eNB. Although in FIG. 5,the macro eNB 512 is shown as the eNB, in some embodiments the eNB maybe a remote radio head (RRH) with a fiber connection to the macro eNB512. The RRH may have the same physical cell ID (PCI) as the macro eNB512.

Transmission point switching to support seamless UE mobility may beprovided by dynamic point selection, where a combination of RRC and DCIsignaling may be used to indicate the transmission point (the eNB fromwhich the UE is currently receiving data). A potential time andfrequency mismatch between synchronization source and the transmissionpoint may be handled in the frequency domain without changing pre-FFTsynchronization. At the same time, post-FFT compensation may limit thepossible deployment scenarios where such seamless mobility can besupported. For example, in accordance with Technical Report 38.819 inthe context of Release 11 regarding downlink CoMP. UE performancerequirements were defined by assuming timing offset in the range [−0.5,2] μsec. where a substantial portion of the received signal is withinthe CP. In situations in which dynamic switching is used, timing offsetsoutside of this range (i.e., a timing advance of 0.5 μsec or timingdelay of 2 μsec) may lead to inter-symbol interference and corrupt thereceived symbols. Timing offset for dynamic switching may includedifferences in synchronization of the eNBs 512, 522 as well aspropagation delays between the eNBs 512, 522 in transmissions betweenthe eNBs 512, 522 and the UE 502. For a given symbol transmitted by theeNBs 512, 522, a timing offset may correspond to a time difference inthe symbol as received by the UE 502, which may translate to a phaseramp in the frequency domain after FFT processing.

Even if the eNBs 512, 522 are perfectly synchronized using a high-speedbackhaul, the timing offsets may correspond, as shown in FIG. 5, to themaximum difference of the propagation delays between the synchronizationsource (e.g., macro eNB 512, also referred to herein as the servingcell) and the transmission point (e.g., pico eNB 522) is equal to 0.96μs, when the cell radius=289 m (where the inter-site distance (ISD)=500m). Increasing the coverage area of the macro cell 510 to a cellradius >600 m would not allow support of seamless mobility using thelegacy downlink CoMP framework; the handover procedure would introduceinterruption. Similarly, the legacy uplink transmission also targets asingle reception point and is not substantially optimized to supportseamless mobility.

The UE 502 may have the baseband capability for multiple FFT processing.In particular, this capability may be used to support carrieraggregation and dual connectivity, which may allow support of multi-linkconnectivity at the UE 502 through dynamic switching. However, unlikecarrier aggregation, in which different symbols in multiple frequencybands may be received simultaneously and FFT processed, symbols in thesame frequency band may be independently received from the differenteNBs 512, 522 and FFT processed using different timing offsets. This maypermit an increase the range of the macro cell 510 without substantiallyaffecting mobility as the UE 502 may perform control channel monitoring,PDSCH reception and PUSCH transmission using multiple synchronizationsources and reception points with more than one pre-FFT processing.

More specifically, as indicated above, each eNB 512, 522 may transmit avariety of signals including higher layer control signals in RRCtransmissions, cell-specific control signals in PDCCH or ePDCCHtransmissions, reference signals and data in PDSCH transmissions. Thereference signals may include CRS, which may take one of a number ofpatterns as transmitted by each eNB 512, 522. In some embodiments, thePDSCH may be transmitted within OFDM symbols that are not used in any ofthe cells 510, 520 for PDCCH transmission. Similarly, the CRS patterntransmitted by each eNB 512, 522 may be shifted in frequency accordingto the cell ID of that eNB, such that 3 of the 6 shifts providenon-overlapping CRS patterns. This permits reception of CRS signals formeasurement and feedback by the UE 502 to the appropriate eNB 512, 522.The measurement of the CRS signals may permit the UE 502 to measure thetiming offset and adjust the FFT processing accordingly.

To effect this, the serving cell 512 may initially transmit to the UE502 control information parameters for one or more other cells, such astransmission point 522. The parameters may be provided in higher layersignaling, such as via an RRC message during the RRC connection processin which the UE 502 initially attaches to the serving cell 512, e.g.,when the UE 502 first powers on or is handed over to the serving cell512. The control information parameters may be provided, for example,via an RRCConnectionReconfiguration message from the serving cell 512 tothe UE 502. In some embodiments, the control information parameters inthe RRC message may additionally include the parameters of an ePDCCH,such as occupied physical resources of the ePDCCH and one or morereference signal parameters of the ePDCCH. The control informationparameters in the RRC message may include a PCID and correspondingcontrol information about the PSS and SSS and CSI-RS/DRS for the servingcell 512 and one or more other cells. The control information parametersfor a particular cell may also be referred to as a PDCCH set. Thus, theUE 502 may be able to monitor for the control and reference signals fora plurality of cells.

In some embodiments, the RRC message may include the control informationparameters of all neighboring cells. In some embodiments, the RRCmessage may include the control information parameters of only thosecells configured to provide dynamic switching with the serving cell 512.In some embodiments, the RRC message may include the control informationparameters of only those cells configured to provide dynamic switchingwith the serving cell 512.

In some embodiments, the control information parameters provided in theRRC message may be dependent on the configuration of the network. Forexample, control information parameters for more cells may be providedin a network with a denser cell distribution than in a network with asparser cell distribution. In another example, control informationparameters for more cells may be provided in a local network, such aswithin a confined area such as a store or shopping area, than in anon-local network, such as outdoors, even if the cell distribution inthe non-local network is denser than the local network.

In some embodiments, the control information parameters provided in theRRC message may be independent of characteristics of the UE 502, whilein other embodiments provided the control information parameters may bedependent on characteristics of the UE 502. For example, if the UE 502is a machine-type communication UE (MTC UE) and is non-mobile, theserving cell 512 may decide not to include the control informationparameters of other cells in the RRC message. Similarly, if the servingcell 512 determines that the UE 502 is moving slowly relative to thedistance to other cells, from location data provided by the UE 502 orchanges in signal strength for example, the serving cell 512 may decidenot to include the control information parameters of other cells in theRRC message. The control information parameters in the RRC message maybe periodically or aperiodically updated, for example, as with a changein cell status (e.g., a neighboring cell becomes active or inactive) ora change in the UE state (e.g., a change in the speed).

FIG. 7 illustrates a flowchart of a method of physical downlink controlchannel (PDCCH) reception in accordance with some embodiments. FIG. 7may illustrate the operations of one or more of the UE and eNBs shown inFIGS. 1-6. At operation 702, the UE 502 may attach to a serving cell 512and receive one or more parameter sets. Each parameter set may bereceived in an RRC message. The RRC message may be anRRCConnectionReconfiguration message, for example.

At operation 704, the UE 502 may determine whether the parameter setsinclude downlink (DL) parameter sets or an uplink (UL) parameter sets.In some embodiments, both DL and UL parameter sets are included in theRRC message. In other embodiments, only DL or only UL parameter sets areincluded in the RRC message. As indicated above, the parameter sets maybe updated from time to time, either periodically or aperiodically, andmay change not only parameters within the existing type (DL/UL) ofparameter sets but in addition, or instead, may change between types ofparameter sets. Each DL parameter set may include a PCID for aparticular cell, along with PSS and SSS and DRS configurationinformation for the particular cell. The DRS configuration informationmay include, for example CSI-RS parameters for the particular cell. EachUI, parameter set, on the other hand, may include PUSCH and/or SRSconfiguration information for the particular cell.

In response to the RRC message containing DL parameter sets, the UE 502may use the parameters in the RRC message to monitor for and detectreference signals (RS) from the cells at operation 706. In someembodiments, the UE 502 may detect a PSS and SSS along with the PCID ofthe serving cell 512 and/or the transmission point 522. The UE 502 mayalso detect the DRS of the serving cell 512 and/or the transmissionpoint 522.

Using the DRS, at operation 708 the UE 502 may measure the timing andfrequency offset associated with each of the serving cell 502 and thetransmission point 522. In some embodiments, the UE 502 may also use thePSS and SSS to aid in the measurement. The UE 502 may then adjust theFFT window for each FFT of the UE 502 configured to process signalsrespectively from the serving cell 512 and the transmission point 522based on a timing estimation from the reference signal such that themeasured timing offset is within the −0.5 to 2 μsec. The UE 502,however, may not be aware directly about the offset errors relative tothe OFDM symbol boundary. As is evident, the timing offset for FFTprocessing of signals from the transmission point 522 may be differentfrom the timing offset for FFT processing of signals from the servingcell 512.

In some embodiments, the offset determination is performed once, at thetime the UE 502 initially detects the reference signals from aparticular cell. In this embodiment, once the offsets have beenmeasured, the UE 502 may continue to use the measured offsets of theparticular cell so long as the UE 502 is communicating with theparticular cell. In some embodiments, the UE 502 may continue to measurethe reference signals to periodically or aperiodically update theoffsets. Aperiodic updating of the particular cell may occur due to anevent at the UE 502 and/or the particular cell, for example when eitheris powered down or in the event that the UE 502 is moving rapidly inrelation to the range of the particular cell (or changes velocitysubstantially). The UE 502 may also provide reporting to the particularcell or to all cells, for example, to indicate channel conditions andother information to the cell. In some embodiments, the report mayinclude the timing offsets measured by the UE 502. Once the offsets havebeen measured, the UE 502 may store the offsets in memory to use inPDCCH or PDSCH reception, as desired.

At operation 710, the UE 502 may determine whether the PDCCHtransmission is dynamically switched (along with the PDSCH) or static.This is to say that the UE 502 may determine whether the DL parametersets include parameters to determine which PDCCH to monitor (e.g.,either the serving cell 512 or the transmission point 522) for PDSCHdetection or whether the DL parameter sets include parameters todetermine which PDSCH to monitor (e.g., either the serving cell 512 orthe transmission point 522). Note that although PDCCH transmissions arereferred to, the UE 502 may monitor for cPDCCH transmissions in additionto or instead of the PDCCH transmissions.

In some embodiments, the PSS and SSS may include an index that indicateswhich parameter set to use for PDCCH reception. In response todetermining at operation 710 that the PDCCH is dynamic, the UE 502 mayat operation 712 monitor the appropriate PDCCH depending on the index.In some embodiments, the UE 502 may determine from the PDCCH which PDSCHto decode. The UE 502 may thus determine at operation 512 that the PDCCHand consequently PDSCH of the serving cell 512 is to be monitored anddecoded, or that the PDCCH and consequently PDSCH of the transmissionpoint 522 is to be monitored and decoded.

In response to determining at operation 710 that the PDCCH is static,the UE 502 may at operation 714 monitor only the PDCCH of a single cellof all of the PDCCHs in the network. For example, in some embodiments,the UE 502 may monitor only the PDCCH of the serving cell 512. In thisembodiment, the UE 502 may disregard the PDCCH of the transmission point522 as the PDCCH of the transmission point 522 is not used. Despitemonitoring only one PDCCH, however, the PDSCH may be dynamicallyswitched among the cells. Thus, it may be desirable for the UE 502 toresolve which PDSCH to decode for the particular PDCCH detected. ThePDCCH may include a DCI that permits the UE 502 to find and decode thePDSCH. The DCI may be in any DCI format, depending on the desiredtransmission characteristics of the communication link between the UE502 and the cell transmitting the PDSCH. The DCI may contain one or morebits in a new PDSCH field to indicate the PDSCH for the UE 502 tomonitor. Thus, the UE 502 may extract the bits in the PDSCH field, andto determine the appropriate PDSCH to decode.

At operation 716, the UE 502 may decode the appropriate PDSCH. Theappropriate PDSCH is determined independent of whether the PDCCH isdynamic or static, and thus whether the parameter set or the PDCCHindicates which PDSCH to decode. The UE 502 may thus decode the PDSCHusing the PDCCH at operation 712 or operation 714.

In response to determining, at operation 704, that the parameter setincludes UL PUSCH parameter sets for the different cells, the UE 502 maystore the UL PUSCH parameter sets in memory. The UL parameters in the ULPUSCH parameter sets may include parameters to use for transmissions bythe UE 502 to each cell. Each UL set may thus target a specific ULreception point and include UL parameters describing the ULtransmission. Subsequently, the UE 502 may at operation 718 receive anUL DCI in a PDCCH. In this case, the UE 502 may or may not have alreadydetermined the offsets for DL communication with the different cells.

In communicating UL data to the network, it may be desirable for the UE502 to estimate an appropriate transmit power to use as well as a timingadvance for each cell. Using excessive transmit power may unnecessarilyreduce battery life of the UE 502 and may interfere with thecommunications of other UEs, while using too little transmit power mayentail additional repeated transmissions to the cell to allow the cellto build up the signal strength for detection of the symbol, ifpossible. Timing advance may be used to adjust for propagation delayamong UEs having different distances from a particular eNB. The TimingAdvance (TA) may be equal to twice the propagation delay between a UEand the eNB, assuming that the same propagation delay value applies toboth DL and UL communications. The eNB may continuously measure timingof UL signals from each UE and adjust the uplink transmission timing bysending the value of Timing Advance to the respective UE based on uplinkdata (PUCCH/PUSCH/SRS) The eNB may estimate the arrival time, which canthen be used to calculate the TA value. The eNB may estimate the initialTA from the PRACH, which may be used as timing reference for uplinkduring initial access by the UE, radio link failure or handover, sent bythe UE. The eNB may send a TA command in a Random Access Response (RAR).Once the UE is in connected mode, the eNB may continue to estimate theTA and send a TA Command MAC Control Element to the UE if correction isdesired.

The UE 502 may generally estimate the transmit power to the differentcells from the path loss. The path loss may be determined by the UE 502using signal strength of reference signals received at the UE 502 asmeasured by the UE 502 and the transmit power of the eNB, which may beprovided to the UE 502. The DCI received by the UE 502 may contain apower parameter that indicates to the UE 502 whether to increase ordecrease the transmission power to the eNB by a preset increment. Toachieve a substantial transmission power difference, the power of the UE502 may be adjusted by repeatedly transmitting a PDCCH for the UE 502containing a DCI in which the power parameter increase or decrease thetransmission power to the eNB. Unfortunately, while this may be usefulin an environment in which the path loss changes relatively slowly, thismay not be amenable to dynamic switching, in which it may be desirablefor the transmission power to change substantially when the UE 502transmission switches between the serving cell and the transmissionpoint.

To combat this, the UL DCI in the PDCCH received by the UE 502 atoperation 718 may indicate which of the UL PUSCH parameter sets to usefor communication. The UL PUSCH parameter set may include the downlinkreference signal (e.g. DRS or CRS) to be used by the UE 502 to determinethe path loss. This selection of a set of downlink reference signals forone eNB independent of the set of downlink reference signals used foranother eNB, i.e., the downlink reference signals may be the same or maybe different. The actual uplink transmission power for PUSCHtransmission may be calculated by the UE 502 using open-loop powercontrol equations provided in Technical Specification (TS) 36.213v.12.5.0. The UL PUSCH parameter set indicated by the DCI may alsoinclude one or more TA values, where each TA may be configured usinglegacy MAC signaling. The actual TA that that may be used by the UE 502to receive the PUSCH transmission may be indicated in the DCI.

In some embodiments, the DCI may indicate a transmission power to use.The transmission power may be based on the reference signal used by theUE 502 to estimate the path loss. The DCI may contain an indexindicating which UL PUSCH parameter set to use, and each UL PUSCHparameter set may also be associated with a particular initialtransmission power and TA associated with that DCI index. In someembodiments, the DCI format may contain one or more bits in a new fieldto indicate the power level and one or more bits in another field toindicate the TA. In some embodiments, the serving cell 512 may transmita DCI format 0 or 4, which may contain the power control information.

A similar embodiment to support seamless mobility may be configured foruplink control and SRS. More specifically, one or more SRS transmissionparameters may be configured for the UE 502 using higher layersignaling. The actual transmission set for SRS transmission may beselected by the UE 502 based on DCI triggering the SRS transmission. TheSRS transmission parameters may include a TA and downlink referencesignal (DRS or CRS) to be used to derive the path loss for the uplinktransmit power equation described in TS 360.213 v.12.5.0.

After determining the appropriate UL PUSCH parameter set to use from theDCI, the UE 502 may transmit the indicated reference signals. The UE 502may then estimate the path loss and calculate the transmission power, aswell as determine the TA to use, from a response from the cell indicatedin the UL PUSCH parameter set. The UE 502 may subsequently, at operation720 transmit PUSCH data to the cell indicated in the UL PUSCH parameterset using the calculated transmission power and TA.

FIG. 6 illustrates CoMP using multiple Fast Fourier Transform (FFT)processes in accordance with some embodiments. Rather than relying onpost-FFT synchronization, in which the FFT of the serving cell 610(e.g., eNB 512 in FIG. 5) and transmission point 620 (e.g., eNB 522 inFIG. 5) partially overlap the CP, as shown in FIG. 6, the constraintbetween the FFT window 614, 624 and the CP 612, 622 is more relaxed. TheFFT window 614, 624 may include a PDSCH symbol to be processed by theFFT and other components, for example, to demodulate the PDSCH symbol tobaseband and decode the PDSCH symbol. As shown, the FFT window 614 andCP 612 of the serving cell 610 may be permitted to entirely overlap theFFT window 624 and the CP 622 of the transmission point 620 as the UEmay be able to switch between receiving signals from the serving cell610 and the transmission point 620.

The UE may thus perform control channel monitoring using multiplesynchronization sources with more than one FFT processing. The UE may beconfigured with one or more PDCCH, PDSCH and/or PUSCH sets, where eachPDCCH and PDSCH set may be configured with a PSS and SSS and DRS (orother reference signal) corresponding to the transmission source andeach PUSCH may be configured with a reference signal to use for pathloss estimation and transmission power calculation and TA. Based on theconfiguration, the UE may perform PDCCH demodulation using pre-FFTprocessing in accordance with the timing and frequency offsets derivedfrom the reference signals and PUSCH transmission based on thecalculated transmission power and TA.

Although an embodiment has been described with reference to specificexample embodiments, it will be evident that various modifications andchanges may be made to these embodiments without departing from thebroader spirit and scope of the present disclosure. Accordingly, thespecification and drawings are to be regarded in an illustrative ratherthan a restrictive sense. The accompanying drawings that form a parthereof show, by way of illustration, and not of limitation, specificembodiments in which the subject matter may be practiced. Theembodiments illustrated are described in sufficient detail to enablethose skilled in the art to practice the teachings disclosed herein.Other embodiments may be utilized and derived therefrom, such thatstructural and logical substitutions and changes may be made withoutdeparting from the scope of this disclosure. This Detailed Description,therefore, is not to be taken in a limiting sense, and the scope ofvarious embodiments is defined only by the appended claims, along withthe full range of equivalents to which such claims are entitled.

Such embodiments of the inventive subject matter may be referred toherein, individually and/or collectively, by the term “invention” merelyfor convenience and without intending to voluntarily limit the scope ofthis application to any single invention or inventive concept if morethan one is in fact disclosed. Thus, although specific embodiments havebeen illustrated and described herein, it should be appreciated that anyarrangement calculated to achieve the same purpose may be substitutedfor the specific embodiments shown. This disclosure is intended to coverany and all adaptations or variations of various embodiments.Combinations of the above embodiments, and other embodiments notspecifically described herein, will be apparent to those of skill in theart upon reviewing the above description.

In this document, the terms “a” or “an” are used, as is common in patentdocuments, to include one or more than one, independent of any otherinstances or usages of“at least one” or “one or more.” In this document,the term “or” is used to refer to a nonexclusive or, such that “A or B”includes “A but not B,” “B but not A,” and “A and B,” unless otherwiseindicated. In this document, the terms “including” and “in which” areused as the plain-English equivalents of the respective terms“comprising” and “wherein.” Also, in the following claims, the terms“including” and “comprising” are open-ended, that is, a system, UE,article, composition, formulation, or process that includes elements inaddition to those listed after such a term in a claim are still deemedto fall within the scope of that claim. Moreover, in the followingclaims, the terms “first,” “second,” and “third,” etc. are used merelyas labels, and are not intended to impose numerical requirements ontheir objects.

The Abstract of the Disclosure is provided to comply with 37 C.F.R.1.72(b), requiring an abstract that will allow the reader to quicklyascertain the nature of the technical disclosure. It is submitted withthe understanding that it will not be used to interpret or limit thescope or meaning of the claims. In addition, in the foregoing DetailedDescription, it can be seen that various features are grouped togetherin a single embodiment for the purpose of streamlining the disclosure.This method of disclosure is not to be interpreted as reflecting anintention that the claimed embodiments require more features than areexpressly recited in each claim. Rather, as the following claimsreflect, inventive subject matter lies in less than all features of asingle disclosed embodiment. Thus the following claims are herebyincorporated into the Detailed Description, with each claim standing onits own as a separate embodiment.

1-25. (canceled)
 26. An apparatus of user equipment (UE), the apparatuscomprising: processor configured to cause the UE to: receive, in anradio resource control (RRC) message, a plurality of downlink (DL)parameter sets, the respective DL parameter sets comprising informationof an associated Primary Synchronization Signal (PSS), an associatedSecondary Synchronization Signal (SSS), and an associated physicaldownlink control channel (PDCCH); detect a PSS and/or SSS associatedwith a first parameter set of the plurality of parameter sets; anddynamically switch to receive a PDCCH and a physical downlink sharedchannel (PDSCH) associated with the first parameter set of the pluralityof parameter sets.
 27. The apparatus of claim 26, wherein the PDSCH isindicated by the PDCCH.
 28. The apparatus of claim 26, wherein the PSSand/or SSS associated with the first parameter set includes an indexthat indicates use of the first parameter set for PDCCH reception. 29.The apparatus of claim 26, wherein the processor is further configuredto cause the UE to: decode a PSS and/or SSS associated with a secondparameter set of the plurality of parameter sets; and determine a timingand frequency offset associated with the second parameter set.
 30. Theapparatus of claim 26, wherein the PDCCH comprises an enhanced PDCCH(ePDCCH).
 31. The apparatus of claim 26, wherein the PDCCH includesdownlink control information (DCI), the DCI indicating which of theparameter sets for the UE to use for an uplink transmission.
 32. Theapparatus of claim 26, wherein the processor is further configured tocause the UE to determine path loss associated with the first parameterset.
 33. A user equipment device (UE), comprising: a radio; andprocessor operably connected to the radio and configured to cause the UEto: receive, in an radio resource control (RRC) message, a plurality ofdownlink (DL) parameter sets, the respective DL parameter setscomprising information of an associated Primary Synchronization Signal(PSS), an associated Secondary Synchronization Signal (SSS), and anassociated physical downlink control channel (PDCCH); detect a PSSand/or SSS associated with a first parameter set of the plurality ofparameter sets; and dynamically switch to receive a PDCCH and a physicaldownlink shared channel (PDSCH) associated with the first parameter setof the plurality of parameter sets.
 34. The UE of claim 33, wherein thePDSCH is indicated by the PDCCH.
 35. The UE of claim 33, wherein the PSSand/or SSS associated with the first parameter set includes an indexthat indicates use of the first parameter set for PDCCH reception. 36.The UE of claim 33, wherein the processor is further configured to causethe UE to: decode a PSS and/or SSS associated with a second parameterset of the plurality of parameter sets; and determine a timing andfrequency offset associated with the second parameter set.
 37. The UE ofclaim 33, wherein the PDCCH comprises an enhanced PDCCH (ePDCCH). 38.The UE of claim 33, wherein the PDCCH includes downlink controlinformation (DCI), the DCI indicating which of the parameter sets forthe UE to use for an uplink transmission.
 39. The UE of claim 33,wherein the processor is further configured to cause the UE to determinepath loss associated with the first parameter set.
 40. A method foroperating a base station, the method comprising: at the base station:transmitting, to a user equipment device (UE) in an radio resourcecontrol (RRC) message, a plurality of downlink (DL) parameter sets, therespective DL parameter sets comprising information of an associatedPrimary Synchronization Signal (PSS), an associated SecondarySynchronization Signal (SSS), and an associated physical downlinkcontrol channel (PDCCH); transmitting a PSS and/or SSS associated with afirst parameter set of the plurality of parameter sets; and dynamicallyswitching to transmit, to the UE, a PDCCH and a physical downlink sharedchannel (PDSCH) associated with the first parameter set of the pluralityof parameter sets.
 41. The method of claim 40, the method furthercomprising coordinating beamforming with a second base station.
 42. Themethod of claim 40, wherein the PDSCH is indicated by the PDCCH.
 43. Themethod of claim 40, wherein the PSS and/or SSS associated with the firstparameter set includes an index that indicates use of the firstparameter set for PDCCH reception.
 44. The method of claim 40, whereinthe PDCCH comprises an enhanced PDCCH (ePDCCH).
 45. The method of claim40, wherein the PDCCH includes downlink control information (DCI), theDCI indicating which of the parameter sets for the UE to use for anuplink transmission.